Project Summary/Abstract The ongoing goal of the Autism Biomarkers Consortium for Clinical Trials (ABC-CT) is to establish electroencephalography (EEG) and eye-tracking (ET) biomarkers that can be used for stratification and/or as sensitive and reliable objective assays related to social function in autism spectrum disorder (ASD) clinical trials. This renewal application seeks to further validate promising measures through three studies designed to enhance and extend the original ABC-CT study: (1) a confirmation study of the original findings in a new cohort using similar design (T1: Baseline, T2: 6 weeks post baseline, T3: 24 weeks post baseline) and sample size/characteristics (200 with ASD, 200 with typical development (TD)); (2) a follow-up study of the original cohort (N=399) to re-administer the biomarker and clinical batteries 2.5-4 years after original ABC-CT enrollment; (3) a feasibility study of parallel EEG and ET biomarkers in preschool-aged (3-5-year-old) children (25 with ASD, 25 with TD). The biomarker and clinical batteries measure key facets of social-communication in ASD using well- validated paradigms appropriate for the intended developmental and cognitive range. The study will rely on the same leadership and five Collaborating Implementation Sites (?Sites?) from the first phase, all highly experienced in multi-site collaborative clinical research using the proposed clinical, EEG, and ET methodologies. The Data Acquisition and Analysis Core (DAAC) will oversee consistent use of scientific standards and methodological rigor for data acquisition, processing, and analytics. The Administrative Core, in coordination with federal partners in this cooperative agreement, will oversee the operations of the sites, Data Coordinating Core (DCC), and DAAC to ensure methodologically and ethically rigorous, efficient completion of scientific aims. The DCC will utilize informatics and technology to develop, maintain, and monitor a robust, secure, HIPAA-compliant data collection, coordination, and storage system to streamline communication and data flow throughout the consortium and ensure organized, secure data management, quality control, and reliable upload to the National Database for Autism Research and NIH/NIMH Data Repositories. The DCC benefits from the Yale Center for Clinical Investigation?s data coordinating and quality assurance experience. The DCC will: 1) anticipate, respond to, and fulfill the informatics needs of the consortium in the design, harmonization, and implementation of data coordination and innovative data collection methods and tools across consortium components and studies for collection and management of EEG, ET, and clinical measures; 2) provide state-of-the-art methods in support of these studies for: a) consortium communication; b) data management, site monitoring, privacy, and security within the consortium and across sites; and c) the dissemination of information to stakeholders.